command line 'alsamixer' has all muted except Master and PCM which are set to maximum volume (read various sites saying to mute Capture inputs and Headphone Jack Sense, so that rules them out) - i've also tried unmuting them all and various combinations.

after spendig several hours trying to fix my audio i finally came up to a fine solution (thanks to google and the guys that made the patch!!!).
(i have an intel hd sound integrated in the i915 chipset and fedora 3 installed)

This is what i ve done to fix it.

install fedora 3 first then download a new kernel (the source code, 2.6.11.6 worked for me) and this patch:

alsa-bk-2005-03-02.patch.gz

copy the kernel in /lib/modules, "untar" it and copy the patch into the new kernel directory then run the patch with this command:

patch -p1 <alsa-bk-2005-03-02.patch.gz

then compile the new kernel:
make mrproper
make menuconfig (where you need to check the module for hd intel under the sound card section: you can find it by selecting "device drivers" then "sound" then "Advanced sound linux architecture", "pci devices" where you need to configure the line where it says "hd intel" as a module, should be the last one!)
make
make bzImage
make modules && make modules_install
cp arch/i386/boot/bzImage /boot/vmlinnuz-[kernel version]
/sbin/mkinitrd /boot/initrd-[kernel version].img [kernel version]
then configure your boot loader (grub lilo or whatever )

after rebooting the system with your new kernel just run alsamixer to pump up the volume (pay attention that this is set to mute for default so you need to unmute by pressing m on the selected column)
To avoid misunderstanding run alsamixer then look at the top left where you should now read:
Card: HDA intel
Chip: Realtek ALC260
Item: [whatever you selected, can be headphone or microphone etc etc] [Off]

Press m and you should get rid of the [Off] option. Raise the volume and you should be set to go.

you don't need to run alsaconf at all, i even suggest you not to run it because when i tried to it ruined the configuration and i had to spend some time fixing it.

This should be a temporary solution, as far as i am concerned a kernel that support hd intel sound on the new i915 chipset didn't came out yet (since i installed this patch i could have sound but with skype, anyway it works great with mplayer and all the other programs i have tested)

I am a newbie to linux... and I had this same problem - AC97 motherboard card. I tried everything... I recompiled the kernel... but couldn't figure it out to install it.

I did, however, download the ALSA packages and recompile them, namely, 1st - driver, 2nd the library, then 3rd the utilities and tools. I'm not sure if that helped or not though...

What finally helped me, was I opened up kmix (the mixer window). I turned the volume up on all of the channels (supposably by default they are all set to 0). Still... though, no sound. Then I went to switches tab, and played with those. I turned off IEC958 Capture Monitor... and like magic, it worked!!!! I'm so happy! So... if you're still struggling, I suggest you play with those switches in Kmix!

I'm not experienced... but... hopefully this will help some poor other user out there like me to get there sound card configured.